PROJECT SUMMARY/ABSTRACT HIV pre-exposure prophylaxis (PrEP) has been shown in efficacy and effectiveness trials to achieve high levels of protection, with over 95% protection among those with measurable levels of medication that indicate adherence. This provides a substantial public health opportunity, with the US Centers for Disease Control and Prevention (CDC) estimating that approximately 1.2 million US adults are eligible for PrEP, including 492,000 MSM. PrEP prescriptions are growing exponentially, with over 79,000 prescriptions between 2012 and 2015 in the US. Guidance issued by CDC and by WHO calls for quarterly follow-up visits for those on PrEP, to include behavioral and laboratory assessments, and treatment or counseling as needed. Currently, those on PrEP must have in-person visits with their medical provider for such services, a system that places a large burden on both providers and patients. If PrEP were to be scaled up to cover eligible, high-risk MSM in the United States, we estimate over 1.5 million yearly patient visits would be required, a substantial burden on clinics seeking to bring PrEP to scale. A related problem with bringing PrEP to scale is that patients may not persist in PrEP care over time. This is particularly concerning because those patients in demographics with highest risk for HIV acquisition, young and Black MSM, have been observed to be more likely to not persist in PrEP care over time. The proposed research seeks to make PrEP scale-up more feasible and to increase persistence in PrEP care, by developing a home-based monitoring and support system that would alleviate the need for quarterly, in- person provider visits. We propose to conduct a randomized, controlled trial to determine whether participants (half Black, half aged 18-34) randomized to the home care PrEP system have higher levels of retention in PrEP care relative to standard of care control participants, as determined by biomarker and self-report. The trial will be conducted at sites in Atlanta, GA, Boston, MA, Jackson, MS, and St. Louis, MO. We will also conduct a mixed-methods assessment of trial results, and assess the cost-effectiveness of the home care system.